ORIGINAL ARTICLE

Mutations of human TMHS cause recessivelyinherited non-syndromic hearing lossM I Shabbir*, Z M Ahmed*, S Y Khan, Saima Riazuddin, A M Waryah, S N Khan,R D Camps, M Ghosh, M Kabra, I A Belyantseva, T B Friedman, Sheikh Riazuddin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

See end of article forauthors’ affiliations. . . . . . . . . . . . . . . . . . . . . . .

Correspondence to:ProfessorSheikhRiazuddin,National Centre ofExcellence in MolecularBiology, University of thePunjab, 87 West CanalBank Road, Thokar NiazBaig, Lahore 53700,Pakistan; riaz@lhr.comsats.net.pk

Received24 November 2005Revised version received19 January 2006Accepted for publication24 January 2006Published Online First3 February 2006. . . . . . . . . . . . . . . . . . . . . . .

J Med Genet 2006;43:634–640. doi: 10.1136/jmg.2005.039834

Background: Approximately half the cases of prelingual hearing loss are caused by genetic factors.Identification of genes causing deafness is a crucial first step in understanding the normal function of thesegenes in the auditory system. Recently, a mutant allele of Tmhs was reported to be associated withdeafness and circling behaviour in the hurry-scurry mouse. Tmhs encodes a predicted tetraspan protein ofunknown function, which is expressed in inner ear hair cells. The human homologue of Tmhs is located onchromosome 6p.Objective: To determine the cause of deafness in four consanguineous families segregating recessivedeafness linked to markers on chromosome 6p21.1-p22.3 defining a novel DFNB locus.Results: A novel locus for non-syndromic deafness DFNB67 was mapped in an interval of approximately28.51 cM on human chromosome 6p21.1-p22.3. DNA sequence analysis of TMHS revealed ahomozygous frameshift mutation (246delC) and a missense mutation (Y127C) in affected individuals oftwo families segregating non-syndromic deafness, one of which showed significant evidence of linkage tomarkers in the DFNB67 interval. The localisation of mTMHS in developing mouse inner ear hair cells wasrefined and found to be expressed briefly from E16.5 to P3.Conclusions: These findings establish the importance of TMHS for normal sound transduction in humans.

There are approximately 100 genes that are associatedwith hearing loss in the mouse.1 In humans, more than47 deafness loci have been mapped and 21 of the

corresponding genes have been identified.2 3 Because of thesimilarities in the morphology of their auditory systems, deafmice have provided a valuable resource for understanding thepathophysiology of human hereditary hearing disorders andthe normal functions of these genes. Molecular geneticstudies of deaf mice have been instrumental in identifying sixorthologous deafness genes in humans, including MYO7A(USH1B), MYO15 (DFNB3), TMIE (DFNB6), PCDH15(DFNB23/USH1F), WHRN (DFNB31), and SANS (USH1G).4–15

When a novel human deafness locus is mapped, thequestion arises as to whether or not there is a strain of deafmouse that carries a mutated gene at a chromosomal mapposition suggesting conserved synteny with a human locusfor deafness. Positional cloning in the mouse or phenotypicrescue using a BAC transgene13 16 can lead to gene identifica-tion more quickly than sequencing human genes in a largechromosomal interval of a deafness locus.17 Alternatively,identification of a gene responsible for deafness in a mousemay suggest a candidate human chromosomal location toscreen for linkage of deafness segregating in large familiesthat have a structure suitable for providing significantevidence of linkage.18 A combination of two of thesestrategies was used to identify mutations of TMHS(MIM_609427) as the gene on human chromosome 6p21.1-p22.3 responsible for non-syndromic deafness DFNB67,segregating in two consanguineous families.

METHODSFamily enrolmentApproval for the study was obtained from the institutionalreview board at the National Centre of Excellence inMolecular Biology, Lahore, Pakistan (FWA00001758), the

NIDCD/NINDS IRB at the National Institutes of Health,Bethesba, Maryland, USA (OH-93-N-016) and the institu-tional review board at the All India Institute of MedicalSciences, Delhi, India (FWA00001997). Written informedconsent was obtained from all the participants. FamiliesPKDF374, PKDF619, and PKDF638 were ascertained fromSindh, Pakistan and family HTN-09 lives in Chennai, India.The inheritance patterns of deafness segregating in familiesPKDF374, PKDF619, PKDF638, and HTN-09 are consistentwith an autosomal recessive trait (fig 1).

Clinical evaluationAll participating members of these families were evaluated bya physician to rule out obvious extra-auditory phenotypesassociated with common syndromic forms of deafness. Airconduction pure tone audiometry tests were carried outunder quiet ambient conditions at octave frequencies rangingfrom 250 to 8000 Hz. Vestibular function was evaluated bytandem gait and Romberg testing.

Linkage analysisGenomic DNA was extracted from peripheral venous bloodsamples by a standard protocol.19 Samples were genotyped formarkers flanking known DFNB loci, using marker informa-tion provided by the Hereditary Hearing Loss Homepage (asof August 2004 http://webhost.ua.ac.be/hhh/). For genome-wide screens, we used the ABI Prism v2.5 Linkage MappingSet (panels 1 to 27; Applied Biosystems, Foster City,California, USA) containing 388 fluorescently labelled micro-satellite markers spaced at an average interval of 10 cM.Short tandem repeat polymorphisms (STRPs) were amplifiedby polymerase chain reaction (PCR), alleles were assignedusing Genescan 3.7 and Genotyper 3.7 (Applied Biosystems),and LOD scores were calculated using LINKMAP asdescribed.9 20 21

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Candidate gene screeningCandidate genes were identified using the UCSC GenomeBioinformatics web browser (http://genome.ucsc.edu/) andselected for mutation screening on the basis of their potentialrole in the inner ear. Primers used for PCR amplification andsubsequent sequencing of COL11A2 and TMHS exons weredesigned using the Primer3 Web site (http://frodo.wi.mit.edu/cgi-bin/primer3/primer3_www.cgi). PCR primers are fromsequence flanking each exon (supplementary tables 1 and 2;the supplementary tables can be seen on the journal website:http://www.jmedgenet.co/supplemental). Amplification,sequencing reactions, and mutation analysis were carriedout as described.8

ImmunocytochemistryIn order to characterise in greater detail the cellular localisa-tion and developmental profile of TMHS with immunofluor-escence confocal microscopy, we used a previously reported

affinity purified rabbit polyclonal antiserum generouslyprovided by Ken Johnson.22 Immunostaining was carried outas described.11 23 After fixation in 4% paraformaldehyde fortwo hours at room temperature, organs of Corti and vestibularend organs of mice were dissected in phosphate bufferedsaline (PBS). Samples were permeabilised in 0.5% Triton X-100 for 30 minutes and then washed in PBS. Non-specificbinding sites were blocked using 5% normal goat serum (LifeTechnologies, Gaithersburg, Maryland, USA) and 2% bovineserum albumin (ICN, Aurora, Ohio, USA) in PBS. Sampleswere incubated for two hours in the anti-mTMHS antiseraat a concentration of approximately 5 mg/ml in blockingsolution. After three rinses in PBS, samples were incubatedin a 1:200 dilution of the FITC conjugated anti-rabbit IgG for30 minutes, washed again three times with PBS, mountedusing the ProLong Antifade kit (Molecular Probes, Eugene,Oregon, USA), and viewed with a LSM510 Zeiss confocalmicroscope.23

1 2I PKDF374

1 2II

3 4

1 2

13211113

40.1444.4148.2648.2649.5060.4466.3768.65

cMD6S1660D6S276D6S439D6S1645D6S291D6S1575D6S282D6S1650

Marker22132224

III31323331

32132222

1 6

22132224

40.1444.4148.2648.2649.5060.4466.3768.65

cMD6S1660D6S276D6S439D6S1645D6S291D6S1575D6S282D6S1650

Marker32132222

IV 5

13211113

31323331

22132224

31323331

4

22132224

32132222

3

32132222

2

22132224

32132222

22132224

1 2I HTN-09

1 2II

3 4

3 4

231412

44.4148.2648.2649.5060.4461.86

cMD6S276D6S439D6S1645D6S291D6S1575D6S1549

Marker313245

III5

313245

44.4148.2648.2649.5060.4461.86

cMD6S276D6S439D6S1645D6S291D6S1575D6S1549

Marker

cMMarker

313245

313245

313245

313245

313245

313245

121321

121321

313245

1 4IV 32

1 2I PKDF638

1 2II

3 4

1 2

211112

29.3035.6640.1444.4147.1048.26

cMD6S289D6S422D6S1660D6S276D6S1611D6S439

Marker121311

III

211112

29.3035.6640.1444.4147.7148.26

cMD6S289D6S422D6S1660D6S276D6S1611D6S439

Marker211111

12123113

29.3035.6640.1444.4147.7148.2649.5053.81

D6S289D6S422D6S1660D6S276D6S1611D6S1645D6S291D6S1610

22123112

21211111

29.3035.6640.1444.4147.1048.2649.5053.81

D6S289D6S422D6S1660D6S276D6S1611D6S1645D6S291D6S1610

12123113

12123113

22123112

12123113

22123112

211112

211112

211112

111112

211112

212211

211112

121311

211112

121311

1 6IV 5432

1 2I PKDF619

1 2 3 4

1 2III

II

1 2IV

1V 2

22123113

12332121

4

12123113

12332121

53

21211111

12332121

6

3

4 2

22

Figure 1 Chromosome 6 markers that co-segregate with deafness in families PKDF374, PKDF619, PKDF638, and HTN-09. STR marker positionsare in cM according to the Marshfield human genetic map (http://research.marshfieldclinic.org/genetics/). The linked haplotypes are boxed.Filled symbols denote profound sensorineural hearing loss. The DFNB67 interval is defined by meiotic breakpoints in family PKDF374. Multipointlinkage analyses provided Zmax (maximum LOD scores) of 3.2 for family PKDF374 (markers D6S439 and D6S1645), 1.80 for family HTN-09(markers D6S439 and D6S1645), 2.35 for family PKDF638 (markers D6S276 and D6S1611), and 2.80 for family PKDF619 (markers D6S1660and D6S276).

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RESULTSPhenotypeAffected individuals in families PKDF374, PKDF619,PKDF638, and HTN-09 had congenital bilateral profoundhearing loss. Although, we cannot rule out a mixed hearingloss, the expression pattern of TMHS in the inner ear suggestsa sensorineural deficit. No vestibular dysfunction wasdetected using tandem gait or Romberg testing. Clinicalevaluation revealed no ophthalmological, skin, or renalanomalies. Fundoscopic examination of IV:2 (22 years) andIV:4 (35 years) from family PKDF374 (fig 1) showed no signsof retinitis pigmentosa.

Mapping of DFNB67Over 600 families segregating profound congenital deafnesswere ascertained in Pakistan and were suitable for geneticlinkage analyses. After excluding linkage to known DFNBloci,3 a genome-wide linkage analysis was initially under-taken using DNA samples from four affected and fourunaffected members of family PKDF374. Initial evidence of

linkage was on chromosome 6p21.1-p22.3. Additional shorttandem repeat (STR) markers were genotyped for all theparticipating family members, and haplotype analysisrevealed a region of homozygosity of approximately 29centi-Morgans (cM) delimited by markers D6S1660(40.14 cM) and D6S1650 (68.65 cM) (fig 1). Multipointlinkage analysis provided a Zmax (maximum LOD score) of3.2 for the markers D6S439 (48.26 cM) and D6S1645(48.26 cM). We then discovered three additional families(PKDF619, PKDF638, and HTN-09) segregating deafnessconsistent with linkage to markers in the 6p21.1-p22.3interval (fig 1). The Human Genome Organization (HUGO)(http://www.gene.ucl.ac.uk/hugo) nomenclature committee24

assigned DFNB67 as the designation for this locus for non-syndromic deafness.

Genetic and physical mapA genetic and physical map of the DFNB67 interval is shownin fig 2. This interval has more than 70 annotated genes andapproximately 100 predicted genes (UCSC Genome

PKDF374

6p22

.36p

22.2

6p22

.16p

21.3

16p

21.2

Chr

omos

ome

6

6p21

.1

DFN

B67

Crit

ical

Inte

rval

(~ 2

8.51

cM

)

6p21

.33

6p21

.32

D6S1650 (44.23)68.65

D6S282 (43.34)66.37

D6S1549 (41.49)61.86D6S1575 (41.25)60.44

D6S1610 (39.37)53.81

D6S291 (36.37)49.50D6S1645 (35.69)48.26D6S439 (35.26)48.26

D6S1611 (35.48)47.71

D6S276 (24.29)44.41

D6S1660 (23.42)40.14

D6S422 (20.48)35.66

D6S289 (15.39)29.30cM Mb

HTN-09

PKDF619

Overlappingdeafness loci

Candidategenes

PKDF638

DFNB66

DFNB53 DFNA31 DCDC2 (24.28)SLC17A4 (25.86)SLC17A1 (25.89)SLC17A3 (25.95)SLC17A2 (26.02)

GABBR1 (29.68)

POU5F1 (31.24)

COL11A2 (33.24)SLC39A7 (33.28)

TMHS (35.88)SLC26A8 (36.02)

FGD2 (37.08)KCNK5 (39.26)

KCNK17 (39.37)KCNK16 (39.39)

FOXP4 (41.62)

VMP (24.23)Mb

DFNA13

DFNA21

Figure 2 Chromosome 6p21.1-p22.3 showing the linkage interval of DFNB67. Short tandem repeat (STR) markers are represented by filled circles.The sex-averaged recombination distances in cM and in Mb are indicated along with STR markers. The DFNB67 interval is based on the meioticbreakpoints in family PKDF374. Linkage regions of five overlapping autosomal deafness loci (DFNB53, DFNB66, DFNA13, DFNA21, and DFNA31)are also illustrated. Cytogenetic locations of several candidate genes are indicated. The Mb positions of the markers and the genes are according to theMay 2004 NCBI build 35 of the human genome browser assembly (http://genome.cse.ucsc.edu/cgi-bin/hgGateway).

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Bioinformatics: http://genome.ucsc.edu). COL11A2 was acandidate in these families, as allelic variants of this geneare associated with recessive deafness DFNB5325 and non-ocular Stickler syndrome.3 However, DNA sequence analysisof the 66 exons of COL11A2 from two affected individualsfrom each of the four DFNB67 families did not reveal anydisease associated variants.

Identification of DFNB67 geneTMHS was also a candidate gene for DFNB67 (fig 2) as amissense mutation of the mouse orthologue, Tmhs, wasreported to cause deafness and vestibular dysfunction in thehurry-scurry (hscy) mouse, and TMHS is expressed in theinner ear hair cell stereocilia of mice.22 Like Tmhs, humanTMHS has four exons (NM_182548), which encode a 2162base pair mRNA. The deduced translation of this cDNA yieldsa protein of 219 amino acids that has four predictedtransmembrane helices. We screened the protein codingsequence, adjacent intronic sequence, and the 59 and 39 UTRsof TMHS in two affected individuals from each of the DFNB67linked families. Affected individuals of family PKDF374 hada homozygous deletion of a single nucleotide at position 246(246delC) in the first exon of TMHS (fig 3A), which co-segregated with the hearing loss. This mutant allele ispredicted to cause a frameshift and a subsequent truncationof the deduced protein at amino acid position 84 (P83fsX84;fig 3B). A homozygous missense mutation (380ARG) wasfound in all the affected individuals of family HTN-09(fig 3A). This allele results in an amino acid substitution ofa conserved tyrosine residue at position 127 (Y127C; fig 3,panels B and C). These two mutations (246delC and380ARG) were not found in 200 chromosomes fromethnically and geographically matched normally hearingindividuals from Sindh province of Pakistan and Chennai,India.

TMHS is expressed transiently in inner ear hair cellstereocil iary bundlesFor the developmental profile of the expression pattern ofTMHS, we immunostained the inner ears from P0, P3, andP10 mice. TMHS immunoreactivity was detected in the organof Corti and vestibular hair cells of C57BL/6 mouse as well asin the other cell types such as supporting cells of cochlear andvestibular sensory epithelia, and internal and external sulcuscells of the organ of Corti (fig 4 and data not shown). At highresolution, TMHS immunoreactivity was detected in thekinocilium and along the length of P0 cochlear hair cellstereocilia and appeared to be more concentrated toward thetips (fig 4, panels A to C). A similar pattern was observed inhair cells of the saccular (fig 4, panels D to F) and utricularmaculae (fig 4, panels G to I). The amount of TMHSimmunoreactivity in the stereocilia appears to vary amongdifferent hair bundles. Hair cells with immature stereociliarybundles have a strong TMHS signal but as the hair cellsmature there is a gradual reduction in immunoreactivity(fig 4, panels D and G), consistent with the report by Longo-Guess and co-workers.22 TMHS immunoreactivity in hair cellstereocilia and kinocilia appears at approximately E16.5 andrapidly disappears by P3, after which we could not detect asignal in stereocilia or in kinocilia except in the vestibularsensory epithelium associated with immature hair cells andin the non-sensory cells (fig 4, panels J to L).

DISCUSSIONIn the hscy mouse, a mutation of Tmhs causes deafness andvestibular dysfunction manifested by circling behaviour.22

The identification of recessive mutations of TMHS indicatesan essential role for TMHS in the human auditory system.There are at least two possibilities to explain the discrepancybetween the loss of vestibular function in Tmhs mutant mice22

but not in humans. TMHS may be required for normal

Figure 3 TMHS mutations. (A) Wild type and mutant alleles from unaffected and affected members of families PKDF374 and HTN-09, respectively. (B)Schematic representation of the predicted TMHS structure (modified from Longo-Guess et al22) showing the stop codon P83fsX84 (which is caused bythe 246delC frameshift mutation) in the sequence encoding the first extracellular loop. The missense mutation Y127C is located in the predicted thirdtransmembrane domain. The location of C161F reported for the hscy mouse22 is indicated by an arrowhead. (C) Alignment of TMHS amino acids fromvarious species shows that Y127 (arrow) is conserved (shaded background, similar amino acids; light background, non-conserved amino acids).

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development of mouse vestibular hair cells but is not requiredfor development of human vestibular hair cells. Alternatively,unlike mice, humans may be better able to compensatepartially for loss of vestibular dysfunction by somatosensoryand visual input. Subjects in our study were examined in thefield only by tandem gait and Romberg testing, whichprobably excludes severe bilateral vestibular failure but mayhave missed a more subtle compensated vestibular disorder.More sensitive and informative vestibular testing usingposturography was not available to us in India and Pakistan.

The protein encoded by TMHS is a member of a superfamilyof tetraspan proteins, which includes the claudin tightjunction proteins, gap junction proteins, peripheral myelin,and epithelial membrane proteins as well as calciumchannel-like proteins. Several genes of this superfamily havebeen reported to be necessary for hearing in either humans ormice, or both.1 3 The predicted structure of TMHS consists offour transmembrane helices with two extracellular loops.22

The missense mutation (C161F) previously reported in hscymice may disrupt a disulphide bond present in the secondextracellular loop and destabilise the secondary structure.22

The frameshift mutation that we found in family PKDF374(246delC; P83fsX84) is predicted to introduce a stop codon in

the first extracellular loop (fig 3B). In vivo, the mutantmRNA would either be translated into a truncated TMHSprotein with only one transmembrane domain or be degradedby nonsense mediated decay (NMD).26 The Y127C missensemutation (380ARG) found in family HTN-09 causes asubstitution of the second residue of the third transmem-brane domain of TMHS (fig 3B). Tyrosine is a relatively non-polar hydrophobic amino acid with an aromatic side chain,whereas cysteine is a weakly polar hydrophilic amino acidwith a thiol side chain. The large difference between the twoamino acids may cause disruption of the third transmem-brane domain and may lead to mislocalisation of the encodedprotein.

The disappearance of TMHS from hair cell stereociliarybundles at P3 occurs just before the gradual loss of cadherin23 from stereocilia, which appears to be complete at P16.27 28

A role for TMHS in organising a transient cytoskeleton–membrane interaction in sensory hair cells would beconsistent with the stereociliary pathology found in hscymice22 and the developmental expression profile of TMHS(fig 4).22

We found no disease associated mutations in TMHS orCOL11A2 in affected members of families PKDF619 and

Figure 4 Immunolocalisation of TMHSin the organ of Corti and vestibularsensory epithelia of a P0 C57BL/6mouse. (A to C) Localisation of TMHS incochlear hair cell stereocilia. (A) Anti-TMHS antibody staining (greenchannel). Arrowhead indicates thestaining of kinocilia. (B) Rhodamine-phalloidin staining of filamentous actinin stereocilia of one row of inner haircells and three rows of outer hair cells(red channel). (C) Merged image forTMHS and F-actin (green and red,respectively). (D to F) TMHS wasdetected predominantly in immaturestereociliary bundles of saccular haircells and its expression level decreasesas bundles mature, as previouslyreported.22 The arrowheads in panel Findicate kinocilia labelling of maturestereociliary bundles and residualstaining of the upper portion ofstereociliary bundles. (G to I) In P0utricular hair cells the pattern ofstereociliary staining with anti-TMHSantibody was similar to that of saccularhair cell stereocilia. The arrowheadspoint to intensely stained immature haircell stereociliary bundles and an arrowpoints to a mature hair cell with stainingin the upper portion of the stereociliarybundle. (J to L) In P10 saccule onlyimmature hair cell stereociliary bundles(arrowheads) and non-sensory cells,such as supporting cells (arrow), arestained with anti-TMHS antibodies,while no staining was observed instereociliary bundles of mature haircells. Scale bar in (C), (F), (I), and (L) is5 mm.

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PKDF638. The linkage interval defined by these two families(PKDF619, PKDF638) is approximately 19cM delimited bymarkers D6S289 (29.30cM) and D6S439 (48.26). It is possiblethat these individuals harbour mutations of cis actingregulatory elements of either COL11A2 or TMHS. The deafnesslinked haplotype of affected individuals in family PKDF638excludes the protein coding region of TMHS (fig 2).

There are three additional loci for hearing loss defined bydominant mutant alleles (DFNA13, DFNA21, and DFNA31) atchromosome 6p21.2-p22.3 and two recessive deafness loci(DFNB53 and DFNB66) in this interval (fig 2). In the singlefamily used to map DFNB66, TMHS was screened formutations and none was found.29 It seems plausible that amutation of a second gene in this interval is associated withhearing loss in families PKDF619 and PKDF638. Othercandidates in the 6p21.2-p22.3 interval include five solutecarrier family members (SLC17A1, SLC17A2, SLC17A3,SLC17A4, and SLC39A7), POU5F1, a POU domain containingtranscription factor and c-aminobutyric acid B receptor 1(GABBR1). Genes encoding SLCs and POU domain transcrip-tion factors are important for normal hearing.3 30 Anotherpossibility for not finding mutations in TMHS in two of thefour families (fig 1) is that the LOD scores for deafnesssegregating in PKDF619 and PKDF638 (Zmax 2.80 and 2.35,respectively) do not rise to the level of statistical significancefor linkage, and thus there may be spurious association ofdeafness segregating in these two families with STRs onchromosome 6p. The actual deafness-causing mutations infamilies PKDF619 and PKDF638 may be somewhere else inthe genome.

In summary, we have mapped a new non-syndromicrecessive deafness locus DFNB67 on chromosome 6p21.1-p22.3. In two consanguineous families, we have identifiedtwo likely pathogenic mutations of TMHS that co-segregatewith deafness.

ACKNOWLEDGEMENTSWe are grateful to the members of the four families for theirparticipation in this study and to K Johnson for generously providinganti-TMHS antisera. We also thank Dennis Drayna, Andrew Griffith,Karen Friderici, Shin-ichiro Kitajiri, Rob Morell, Julie Schultz, SabihaNazli, and Saeeda Kalsoom for their suggestions in relation to themanuscript. The study was supported by the Higher EducationCommission, Islamabad, Pakistan; Ministry of Science andTechnology, Islamabad, Pakistan; the International Centre forGenetic Engineering and Biotechnology, Trieste, Italy under projectCRP/PAK02-01 (contract No 02/013); and intramural funds from theNational Institute on Deafness and Other Communication Disorders(1 ZO1 DC000035-07 and 1 ZO1 DC000039-07).

The supplementary tables are accessible on the journalwebsite: http://www.jmedgenet.co/supplemental

Authors’ affiliations. . . . . . . . . . . . . . . . . . . . .

M I Shabbir*, S Y Khan, A M Waryah, S N Khan, Sheikh Riazuddin,National Centre of Excellence in Molecular Biology, Punjab University,Lahore, PakistanZ M Ahmed*, Saima Riazuddin, R D Camps, I A Belyantseva,T B Friedman, Section on Human Genetics, Laboratory of MolecularGenetics, National Institutes on Deafness and Other CommunicationDisorders, National Institutes of Health, Rockville, Maryland, USAM Ghosh, M Kabra, Genetic Unit, Department of Paediatrics, All IndiaInstitute of Medical Sciences, New Delhi, India

*These two authors contributed equally to the work

Conflicts of interest: none declared

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Clinical Evidence—Call for contributors

Clinical Evidence is a regularly updated evidence-based journal available worldwide both asa paper version and on the internet. Clinical Evidence needs to recruit a number of newcontributors. Contributors are healthcare professionals or epidemiologists with experience inevidence-based medicine and the ability to write in a concise and structured way.Areas for which we are currently seeking contributors:

N Pregnancy and childbirth

N Endocrine disorders

N Palliative care

N Tropical diseases

We are also looking for contributors for existing topics. For full details on what these topicsare please visit www.clinicalevidence.com/ceweb/contribute/index.jspHowever, we are always looking for others, so do not let this list discourage you.Being a contributor involves:

N Selecting from a validated, screened search (performed by in-house InformationSpecialists) epidemiologically sound studies for inclusion.

N Documenting your decisions about which studies to include on an inclusion and exclusionform, which we keep on file.

N Writing the text to a highly structured template (about 1500-3000 words), using evidencefrom the final studies chosen, within 8-10 weeks of receiving the literature search.

N Working with Clinical Evidence editors to ensure that the final text meets epidemiologicaland style standards.

N Updating the text every 12 months using any new, sound evidence that becomes available.The Clinical Evidence in-house team will conduct the searches for contributors; your task issimply to filter out high quality studies and incorporate them in the existing text.

If you would like to become a contributor for Clinical Evidence or require more informationabout what this involves please send your contact details and a copy of your CV, clearlystating the clinical area you are interested in, to CECommissioning@bmjgroup.com.

Call for peer reviewers

Clinical Evidence also needs to recruit a number of new peer reviewers specifically with aninterest in the clinical areas stated above, and also others related to general practice. Peerreviewers are healthcare professionals or epidemiologists with experience in evidence-basedmedicine. As a peer reviewer you would be asked for your views on the clinical relevance,validity, and accessibility of specific topics within the journal, and their usefulness to theintended audience (international generalists and healthcare professionals, possibly withlimited statistical knowledge). Topics are usually 1500-3000 words in length and we wouldask you to review between 2-5 topics per year. The peer review process takes placethroughout the year, and out turnaround time for each review is ideally 10-14 days.If you are interested in becoming a peer reviewer for Clinical Evidence, please complete thepeer review questionnaire at www.clinicalevidence.com/ceweb/contribute/peerreviewer.jsp

640 Shabbir, Ahmed, Khan, et al

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